| Background:Paced QRS duration, a good marker of ventricular asynchrony while pacing, has been accepted as a valuable predictor of new onset heart failure in patients receiving right ventricular apical pacing. But nowadays we have little clue to predict paced QRS duration before the implantation.Objective:The purpose of this article is to identify potential predictors of paced QRS duration in patients receiving right ventricular apical pacing for complete atrioventricular block.Methods:One hundred seventy patients with right ventricular apical pacing for complete atrioventricular block were studied. Demographic characteristics, clinical features, electrocardiogram and echocardiography before implantation, and electrocardiogram immediately after implantation, were retrospectively recorded. T-test, Mann-Whitney test, Multivariable linear regression, Pearson correlation test and Receiver operating characteristic curves were employed to reveal the fact.Results:As a whole, paced QRS duration was much longer than native QRS duration (P=0.000). Compared with others, patients with paced QRS duration longer than 170ms had significantly larger increase of QRS duration (P=0.000) and increasing scale of QRS duration (P=0.000). They were more likely to be male (P=0.010). And they had higher height (P=0.033), heavier body weight (P=0.002) and longer native QRS duration (P=0.039). Those patients also had larger left atrial dimension (P=0.034) and left ventricular end-diastolic dimension (P=0.001). By multivariable linear regression analysis, only preimplant left ventricular end-diastolic dimension and body weight were found to be independently associated with paced QRS duration. Though both of them had low sensitivity and specificity in predicting paced QRS duration longer than 170ms, the specificity could increase to 81.2% when they were combined.Conclusion:Both preimplant left ventricular end-diastolic dimension and body weight independently associate with paced QRS duration in patients receiving apical pacing for complete atrioventricular block. Though whether they really have effect on new-onset heart failure still needs to be verified, this finding may be a good clue. Background:Ventricular electrical asynchrony commonly exists in heart failure patients before cardiac resynchronization therapy (CRT). Theoretically, the ventricular electrical synchronicity would be restored after CRT. For example, QRS duration may be shortened. However, QRS dispersion, another index reflecting ventricular electrical synchrcnicity, has rarely been discussed in literature about cardiac resynchronization therapy.Objective:This study was designed to reveal the influence of cardiac resynchronization therapy on ventricular electrical synchronicity and to discuss its prognostic value.Methods:We studied 84 patients with primary CRT implantation and 8 patients who were upgraded to cardiac resynchronization therapy. Change of QRS duration was defined as pre-implant QRS duration minus post-implant QRS duration. And change of QRS dispersion was defined as pre-implant QRS dispersion minus post-implant QRS dispersion. Patients with primary CRT implantation and patients with CRT upgrading were analyzed separately.Results:For patients with primary CRT implantation, both QRS duration and QRS dispersion shortened in general after implantation (P=0.032; P=0.000). Both QRS duration and QRS dispersion shortened in response group too (P=0.007; P=0.000) However, this phenomenon wasn't seen in non-response group. Compared to non-response group, the change of QRS duration was larger (P=0.045) while the change of QRS dispersion was similar. As shown by receiver operative curve, change of QRS duration no longer than 5ms could predict non-response to cardiac resynchronization therapy with a sensitivity of 0.714 and a specificity of 0.611. For patients with CRT upgrading, QRS duration shortened significantly (P=0.001), but there was no significant change in QRS dispersion (P=0.844). Change of QRS duration also seemed to associate with the response to cardiac resynchronization therapy.Conclusion:Cardiac resynchronization therapy can improve patients'ventricular electrical synchronicity. Change of QRS duration had predictive value for non-response to primary cardiac resynchronization therapy.Part III Clinical characteristics of non-responders and super-responders to cardiac resynchronization therapyBackground:Though patients all receive cardiac resynchronization therapy according to the international guideline, their response to this treatment varies to a large extent. If non-responders and super-responders could be identified before implantation, we will be able to recommend cardiac resynchronization therapy to patients who probably benefit more from this treatment.Objective:Our current study was designed to reveal the clinical characteristics of both non-responders and super-responders to cardiac resynchronization therapy.Methods:We included 92 patients who received cardiac resynchronization therapy in our hospital. All patients were divided into 3 groups. Group A was defined as the group of non-responders. Group C was defined as the group of super-responders. And Group B was the group of all responders exclusive of super-responders. We search the characteristics of non-responders and super-responders among patients'demographic information, disease diagnosis, electrocardiographic data and echocardiographic data before and after device implantation.Results:Followed up for 16.4±10.8 months,30 patients entered Group A,18 patients entered Group C, and 44 else patients entered Group B. Group A had more severe pre-implant mitral regurgitation (vs. Group B, P=0.018; vs. Group C, P=0.011), lager 3-month left ventricular end-diastolic dimension (vs. Group B, P=0.047; vs. Group C, P=0.000)and lowest 3-month left ventricular ejection fraction (vs. Group B, P=0.001; vs. Group C, P=0.000). Group C had smallest pre-implant left ventricular end-diastolic dimension (vs. Group A, P=0.000; vs. Group B, P=0.000), shortest post-implant QRS duration (vs. Group A, P=0.002; vs. Group B, P=0.005), largest change of QRS duration (vs. Group A, P=0.001; vs. Group B, P=0.020), smallest 3-month left ventricular end-diastolic dimension (vs. Group A, P=0.000; vs. Group B, P=0.000) and highest 3-month left ventricular ejection fraction(vs. Group A, P=0.000; vs. Group B, P=0.000). Compared with Group A, Group C had smaller post-implant QRS dispersion (P=0.017). However, only pre-implant mitral regurgitation no less than moderate independently related to non-response. Only pre-implant left-ventricular dimension and change of QRS duration independently related to super-response. Furthermore, pre-implant left ventricular end-diastolic dimension no larger than 68.5mm identified super-responders with a sensitivity of 0.889 and a specificity of 0.781. And change of QRS duration no less than 30ms identified super-responders with a sensitivity of 0.647 and a specificity of 0.732. Conclusion:Pre-implant mitral regurgitation no less than moderate was the independent predictor of non-response to cardiac resynchronization therapy. While pre-implant left ventricular end-diastolic dimension and change of QRS duration were independent predictors of super-response to cardiac resynchronization therapy. |
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